Coating composition



Patented .luly 5, 1927.

UNITED STATES 1,634,359 PATENT OFFICE.

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COATING COMPOSITION.

In Drawing. Original application filed December 18, 1928, Serial Io. 680,343. Divided and this application filed July 6,

This invention relates to coating compositions, and its object is to produce a liquid coating composition which may be readily applied to an article and baked thereon to 6 form a hard, tough, flexible and durable coating.

In particular, it is desired to produce a.

In accordance with the general features of the invention, polymerized vegetable oil is used as the basis of a liquid coating com- 30 osition. The vegetable oils .which have V een found most suitable are those, such as tung oil and castor oil, which have the properties of polymerizing and thereafter gelatinizing when heated. Such oils give the bestresults when polymerized to a state just short of gelatinization. To realize this state of gelatinization, the oil may be heated alone for a suitable length of time and then suddenly cooled by the addition of a substance,

as such as rosin oil, in a cold state. Vegetable oils prepared in this way may be spread upon a metallic article and baked thereon to form a hard, flexible, insulating enamel. Inasmuch as a liquid coating composition 85 prepared from vegetable oils alone is slow aking, the polymerized oil is mixed with certain substances which will decrease the time required to bake it on a metallic article and which will, for this reason, considerably all reduce the cost of coating such an article. llhe substances which have been found most satisfactory for this purpose are certain resin glycerides.

A resin, such as Congo copal might be used, but it has been found preferable to use the glyceride of such a. resin both because it may be transformed by heat into a hard substance at a temperature similar to that at which vegetable oils are thus transformed and because the glycerol converts the acid bodies of the resin into substances which are more inert chemically. As such glycerides have a tendency when heat treated to gelatinize in the same manner that certain vege- 1925. Serial 1m, 415w.

make the coating less flexible when heated to.

a degree at which it has the necessary inertness to solvents.

After the addition of the glyceride, the mixture should be heated over a period 9 order that the resulting composition produce a smooth coating when 'ap lied to and baked on the metallic article. T e composition is then spread on the metallic article and baked.

Such a composition bakes rapidl at a temperature, similar to that at whic vegetable oil hardens, and forms an enamel which is hard enough to withstand the treatment to which electrical conductors are normally subjected, which has a toughness greater than that of an enamel formed from vegetable oil alone, which is so flexible that a wirecoated therewith may be sharply bent without cracking the enamel, and which has good insulating properties. Furthermore,

this enamel is very resistant to the solventaction of the benzol or carbon tetrachloride contained in cleaning fluids commonly used upon the enameled conductors, or the linseed oil in certain varnishes with which enameled conductors are often coated, or the denatured alcohol used in shellacs of. the resin-rosin oil combinations, or of the paraflin used in the melted moisture-proofing compositions with which coils of enameled wire are often impregnated, or of the gasoline or benzene contained in various liquids which are likely to come in contact with enameled conductors.

Certain examples illustrating the above processes are given below to enable the invention to be more readil practiced. When proportions are given ey are by weight unless otherwise stated.

Tung oil (Chinese wood oil) any of the followin ways:

(cl One part of glycerol is added to is treated in f 70 time, and solventsfiadded, if necessary, in

' cooled by the addition of twelve parts of cold rosin oil having an acid number of five or less.

.In this example,the glycerol performs the double function of delaying gelatinization of the oil in case it is overheated before the addition of the rosin oil, and of rendering the coating composition less acid, and hence making it capable of producing a baked coating which is very inert to solvents.

(b) Tung oil is heated at a temperature not to exceed 220 C. to a point approaching gelatinization and then mixed with cold rosin oil. 1

The glyceride of Congo copal may be 4 formed in any of the following ways:

(a') Two or more parts of rosin oil (preferably having a hi h boiling point) are added to one part of ongo copal and the mix ture heated at between 275 C. and300 C. for two hours or until the copal is entirely fused. One gallon of glycerol for each fourteen pounds of Congo copal used is then added to the mixture and the temperature maintained at between 280 C. and 300 C. for about one hour. At the completion of this heating the mass will still contain a considerable amount of uncombined copal and the above treatment with glycerol is repeated until the acid number of the mixture is re-- duced to about ten. If apparatus is used w ich will prevent to a certain extent the volatilization of the glycerol, all the glycerol may be added at once. During the treatment with glycerol, the ratio of rosin oil to copal should be maintained at not less than two to one.

(6') Con o copal is fused until it has lost .20 to 35% 0 its weight. To one part of this fused copal is added two parts of rosin oil. Glycerol is then added and the process continued in either of the ways indicated in a above. i

(0') Congo copal is fused with an equal portion of rosin, the resultant product heated with glycerol preferably in the presence of rosin oil'and the process continued as in a above.

(d') Three parts of Congo copal are fused as described in my Patent 1,422,861, on July 18, 1922 with two parts of those fatt acids derivable from tung oil by saponi cation. Suflicientglycerol to neutralize both the resin and the atty acid is then added and the mixture heated preferably in the presence of rosin oil in the manner described in a above. A certain amount of tung oil is formed from the glycerol and the tung oil fatty acids and is then polymerized by the heating.

of resin glyceride as prepared in either (a'), 1 i

Three parts of of the mixture of resin glyceride and polymerized tung oil prepared as in (d).

The resultant mixture is heated for about six hours when a suitable proportion of volatile solvent, such as benzene or high-flashnaphtha, is added. This composition may be applied to the article to be coated and is baked thereon at a temperature of about 300 C. to drive off the benzene or naphtha, any excess glycerol, and the rosin oil, and to harden the coating. If a thicker coating is desired, the application and the baking process may be repeated as often as necessary.-

treated tung oil to one part Any substance which will perform a like I function should be considered as the equivalentof any of the substances mentioned in the specific examples described above.

Castor oil, corn oil, soy bean oil, rape-seed oil, sesame oil, cottonseed oil and peanut oil, for instance, may be used in place of either tung oil or the linseed oil and either of these oils may replace the other. Other resin oils may be used in place of the rosin oil.

Manila copal and shellac are examples of other resins which will form gelatinizable esters with glycerol and are adapted for use in this invention.

Actual practice has shown that the coating composition in this invention may be applied in thicker coatin s than the ordinary enamels and yet pr uce a smooth even product.

What is claimed is:

, 1. The process of producing a liquid coating composition which comprises heating gelatinizable vegetable oil, adding cold rosin oil thereto, m'xing therewith a substance which will gi e a quick baking (quality to the liquid coating composition, an heating the mixture. 2. The process of producing a liquid coating composition w ichcomprises adding g1 cerol to neutralize the acid bodies of a substance having a quick baking quality, heatin gelatinizable vegetable oil, and ad ing co d rosin oil thereto, mixing the products so formed, and heating the resulting mixture.

3. The process of producing a liquid coating composition which comprises heating ge atinizable vegetable oil and adding a rosin oil thereao; heating resin and rosin oil, adding glycerol thereto and heating the mixture; mixing the products so formed, and heatin the mixture.

4. T e process of producing a liquid coating composition which comprises heating resin and rosin oil, adding thereto suflicient glycerol to produce a glycerol ester of said resin having a low acid number and heating the mixture, heating gelatinizable vegetable oil and adding rosin oil thereto, mixing the products so formed, and heating the resulting mass.

5. The process of producing an insulating enamel which comprises heating gelatinizable vegetable oil, adding thereto a substance which will arrest the gelatinization thereof, adding glycerol to a mixture of rosin oil and resin and applying heat thereto; mixing the products so formed, heating the mixture, diluting the resulting mass with a volatile solvent, applying the diluted mass to the surface to be coated, and baking it thereon.

6. The process of producing a liquid coating composition which comprises heating vegetable oil, adding cold rosin oil thereto, forming a gelatinizable glycerol ester of y resin in the presence of a substancewhich will prevent the gelatinization of said ester, mixing the products so formed, heating the mixture, and adding a volatile solvent.

7. The process of forming a liquid coating composition which comprises heating vegetableioil and adding cold rosin oil there'- to, heating a mixture of resin, rosin oil and.

glycerol, mixing the products so formed,

heating the resulting mixture, and diluting with a volatile solvent.

8. The process of producing a liquid coating composition which comprises heating tung oil and adding rosin oil thereto, heating glycerol with a mixture of Congo copal and rosin oil, mixing the products so formed, and heating the mixture.

9. The process of producing a liquid coating composition which comprises heating tung oil with glycerol and adding rosin oil thereto, heating glycerol with a mixture of Congo copal and rosin oil, mixing the products so formed, and heating the mixture.'

10. The process of producing a liquid coating composition which comprises heating tung oil with a smaller amount of glycerol, adding rosin oil thereto, and mixing therewith resin glyceride.

11. The process of producing a liquid coating composition which comprises fusing Con o copal, adding glycerol thereto, and heating to esterity the Congo copal in the presence of at least two times its weight of rosin oil, heating tung oil with a smaller quantity of glycerol, adding cold rosin oil thereto, mixing this product with the Congo copal ester mixture, heating the resulting mixture, and diluting the heated mass.

In witness whereof, I hereunto subscribe my name this 3rd da of July A. D., 1925.

- CZKRL D. HOCKER. 

